The invention relates to an outwardly curved vehicle door, in particular for motor vehicles having a correspondingly curved side windowpane.
In the prior art, the central supporting element forming the function carrier of a passenger vehicle or truck door consists of a deep-drawn steel sheet having a material thickness of between 0.8 and 1.2 mm. Although the steel sheet forms an encircling, closed edge, the supporting steel sheet has to have relatively large apertures and cutouts for installation work on the door lock, on the windowpane, on the lifting mechanism for the windowpane and on other add-on parts of the door. These necessary apertures and cutouts in the steel sheet reduce the stability of the door in the event of a crash and are the reason for relatively low strength values in all load situations. Moreover, the large cutouts in the region of the outer door covering mean that water easily penetrates, which can be prevented only to an unsatisfactory extent by sealing films and cannot be prevented sufficiently reliably in the long term. In addition, the relatively large cutouts in the supporting steel sheet necessitate complex means for fastening the door add-on parts making relatively large tolerances necessary in regard to the securing of the door coverings. The installation of conventional vehicle doors is particularly complex and time-intensive, since all of the accessory parts have to be assembled by hand on the manufacturing assembly line and are difficult to gain access to on the supporting steel sheet. In order largely to be able to counteract the deficient stability of the steel sheet as the function carrier of the conventional vehicle doors, special reinforcements have to be provided which protrude relatively far out of the plane of the steel sheet, as a result of which the known vehicle doors constitute a particularly bulky structural body which requires an unsatisfactorily large structural space between the door outer covering or the outer skin and the function carrier.
This relatively large structural space of the vehicle door, which is curved outward to a greater or lesser extent and has a particularly large structural depth or strength, is necessitated by the curvature of the door and the correspondingly curved side windowpane which is connected to a window lifting and lowering system which, in the prior art, comprises a scissors-type mechanism or a device having a control cable, it being possible for these known window lifting and lowering systems to be operated by motor. In this case, however, the known systems take up a necessarily uncurved section of space within the curved door over the height of the complete window closing and opening path, which means in many cases taking up up to 60 mm in spatial depth which could be saved if there were a window lifting and lowering system which does not require an uncurved section of space within the curved vehicle door with its correspondingly curved side window and at the same time may also be provided with a drive by motor.